If you disliked HT in the Pentium 4, take another look at it today. The Pentium 4 had four dispatch ports and not too many execution units - a single thread was

If you disliked HT in the Pentium 4, take another look at it today. The Pentium 4 had four dispatch ports and not too many execution units - a single thread was able to exploit that. The i7, in contrast, has 6 dispatch ports feeding 12 execution units. It's extremely difficult to find instruction-level parallelism within a single thread that can exploit that architecture, hence the need for HT to keep the execution units cranking. These days it's quite rare to find applications which are slowed by HT.